overheating and coolant not circulating?

sometimes when my car sit for hours like over night and when I first start it up. there is a high squealing noise for like 5 seconds or so. when I drive my car for 2hours or more my car starts to overheat especially if I'm waiting at a stoplight. I pull over and waited for the car to cool down. I opened my hood and look in the coolant resirvore and it was full max out all the way to the top. then I opened the radiator cap and look in I cant see any coolant. I have to add coolant to the radiator. It usually take like half a quart of coolant to fill it back up. I go back to start my car and the temperature went back to normal. like I said this only happens if I drive for 2 hours or more straight then the temp gauge will start to go up towards the H. what is the cause of this overheatting?,

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  • 9 months ago
    Favourite answer

    Before you start your car in the morning, check the reserve tank and see where the level is and the radiator. If the radiator is empty then the coolant recovery system is not working. If this is the case there should be indications of a leak if a heater hose is bad. But the leak can be the seal on the water pump that is preventing the vacuum from pulling water back in from the over flow tank. The noise when you start the car suggests a water pump problem too or a belt problem. Now if you can open up the radiator when the car has over heated, that to me also suggests a pressurization problem. Maybe a bad radiator cap.

    As for water cooling better with out "anti-freeze", a lot of things have changed from when I was a kid. One of which is the nature of anti-freeze. It is now called "coolant additive" for a reason and that is modern formulas improve heat transfer.

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  • 9 months ago

    Squealing is usually a loose drive belt. If it isn't loose, it may indicate that something is not rolling correctly, like perhaps the water pump. Overheating after awhile, especially while at a stoplight, strongly suggests the car's radiator may be plugged and not rejecting enough engine heat. Since you say the water temps slowly increase, I say with certainty that your radiator is probably the culprit. You can test this by emptying all the coolant and filling with water only and drive. If the car does not overheat with water, you know the radiator needs replacement. Plain water has better heat absorption than water/antifreeze mix. It is not a good idea to leave mostly water in the engine as coolant, it will damage the engine.

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  • 9 months ago

    You've got a bad head gasket. The compression from the cylinders is forcing the coolant out of the radiator and into the reservoir.

    Source(s): Mitsubishi Master Tech
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  • Anonymous
    9 months ago

    The serpentine belt is slipping and needs re-tensioning.

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